This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A050269 #16 Feb 16 2025 08:32:40
%S A050269 1,2,3,4,5,1,3,6,7,8,9,2,4,10,11,12,1,8,13,3,5,14,15,16,17,4,6,18,3,8,
%T A050269 19,20,21,1,2,5,7,12,15,22,23,24,25,6,8,26,27,4,12,28,29,7,9,30,3,16,
%U A050269 31,32,1,24,33,8,10,34,35,36,5,16,37,2,3,9,11,21,24,38,39,4,20,40,41
%N A050269 Smallest value a for Diophantine 1-doubles (a,b) ordered by smallest b.
%H A050269 P. Gibbs, <a href="https://arxiv.org/abs/math/0107203">Diophantine quadruples and Cayley's hyperdeterminant</a>, arXiv:math/0107203 [math.NT], 2001.
%H A050269 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/DiophantusProperty.html">Diophantus Property.</a>
%t A050269 m = 0; Do[If[IntegerQ[Sqrt[a*b + 1]], an[m++] = a], {b, 2, 43}, {a, 1, b}]; Array[an, 81, 0] (* _Jean-François Alcover_, Feb 04 2019 *)
%o A050269 (PARI) an=vector(81); m=0; for(b=2,43, for(a=1,b, if(issquare(a*b+1), an[ m++ ]=a))); an
%Y A050269 Cf. A050270.
%K A050269 nonn
%O A050269 1,2
%A A050269 _Eric W. Weisstein_